1. Field of the Invention
The present invention relates to a method of manufacturing a wiring substrate and to an electronic instrument.
Priority is claimed on Japanese Patent Application No. 2004-282221, filed Sep. 28, 2004, the contents of which are incorporated herein by reference.
2. Description of Related Art
A photolithographic process, for example, is used to form a wiring pattern that forms an electronic instrument. However, not only are large-scale equipment such as a vacuum apparatus and complicated processing necessary in a photolithographic process, but the utilization efficiency of the material is only a low percentage and most of the material ends up being wasted. Consequently, manufacturing costs are high. Furthermore, there is a limit as to how finely detailed the wiring pattern can be made.
Therefore, instead of a photolithographic process, a process is being investigated in which a wiring pattern is directly rendered by ejecting a liquid that contains a functional material onto a base material (i.e., a droplet ejection process). In this process, firstly, liquid lines are formed by ejecting a liquid in which fine conductive particles have been dispersed onto a substrate from an ejecting head. Next, the liquid lines are baked by performing heat processing or laser irradiation so that a wiring pattern is formed (see, for example, U.S. Pat. No. 5,132,248). According to this type of droplet ejection process, because the manufacturing process is simplified and the material utilization efficiency is high, the manufacturing costs can be reduced. Moreover, more finely detailed wiring patterns can also be made.
In recent years, the density level of circuits forming electronic instruments has consistently become higher and there have been demands for further miniaturization and narrower wires in the wiring patterns that make up the circuit. However, if this type of detailed wiring pattern is formed using a method that employs the aforementioned droplet ejection process, after the ejected droplets have landed on a substrate they tend to spread out. As a result, in order to form a detailed wiring pattern accurately and consistently, suitable surface control is necessary.